Inventories (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Mar. 31, 2020
Schedule of Inventories
Refinery feedstocks	$ 1,646		$ 1,646		$ 1,979
Refined petroleum products and blendstocks	3,944		3,944		3,425
Renewable diesel feedstocks and products	113		113		50
Ethanol feedstocks and products	233		233		297
Materials and supplies	291		291		287
Inventories	6,227		6,227		6,038
Inventories (Textual)
LCM inventory valuation reserve						$ 2,500
Lower of cost or market (LCM) inventory valuation adjustment	0	$ (313)	0	$ (19)
Excess of market value over carrying amount of LIFO inventories	5,200		5,200		1,300
Liquidation of LIFO inventory, increase to cost of materials and other		$ 326		$ 326
Amount of non-LIFO inventory	$ 1,200		$ 1,200		$ 918